The invention relates to a battery grip for diagnostic units.
Such battery grips, as known, for example, from DE-PS 1 811 923 B, serve as a light source for medical diagnostic instruments, such as otoscopes, ophthalmoscopes etc. A threaded sleeve made of metal, into which an electric bulb is inserted as a consumer load, is disposed at the upper end of a grip sleeve. Batteries or accumulators are arranged in the grip sleeve, the positive poles of which are attached to the electric bulb and the negative poles of which are connected by means of a biased spring, to a contact strip extending upwards along the inner wall of the grip sleeve to a guide opening for a switching slide. A contact spring is fixed in a conducting manner to the threaded sleeve, the free end of the contact spring extending into the guide opening to such an extent that it is disposed above the contact strip. Normally the contact spring is biased such that it is located at a distance to the contact strip while the switching slide is in a circuit-opening position. When the switching slide is moved from its circuit-opening position to its circuit-closing position, it urges the contact spring against the contact strip so that the circuit is closed and the electric bulb illuminates. Both the contact spring member and the contact strip of the known battery grip are formed in the shape of continuous strips so that a line or area contact between the two members is established when the electric bulb is switched on. However, in some cases it turned out that failure might occur in the case of a very high number of switching cycles.
U.S. Pat. No. 4,866,228 discloses a switch having a stationary contact member and a movable contact member, wherein the contact between both is created through several contact points, which are achieved by a finger-like structure of the free end of the contact spring member disposed above the stationary contact member. By this, increased reliability of the switching contact is to be achieved.
The object of the invention is to create a battery grip by means of a simple design the function of which is always guaranteed even in the case of a very high number of switching cycles.